Whether you already have a collection of makeup brushes, or may just be getting into makeup tools I think it is helpful to keep a few things in mind. First, be realistic. How often do you plan on using makeup brushes? In my experience purchasing a whole set can be a waste of your dollars if you really only use a couple of the brushes included. I prefer to buy my brushes on an as needed basis.
Second, will you take good care of them? The better you take care of your tools the longer they will last. Expensive “investment” brushes/tools should last you a lifetime if well cared for. Even cheap brands can last many years with regular cleanings and proper storage.
Third, how portable does your makeup routine need to be? This might seem like an odd question. If you travel a lot, or tote your makeup kit back and forth to a gym etc., are you comfortable carrying expensive brushes with you? Cheaper brushes are great for putting together an on-the-go kit. Also, if you happen to misplace a brush you won’t be out a wallet-weepingly expensive tool.
The graphic below lists some of my favorite brush brands on a scale by cost. I would highly recommend Sigma Beauty if you really feel the need to purchase a full set of brushes. I use e.l.f. brand brushes in my gym bag and travel kits. Eco Tools makes a pencil brush that has an eye pencil sharpener on the opposite end, and I love their domed bronzer brush (which I use for a variety of reasons other than bronzer).